Pakistan stubbornly refused to concede the first Test in the face of a would-be world record run chase, but a steady trickle of wickets ensured the Australians maintained the upper hand entering the final day. Set an improbable victory target of 422, the tourists headed to stumps in relatively good health at 3 for 170 following an entertaining day that witnessed Shane Watson register a nerve-jangling maiden Test century and Mohammad Aamer become the youngest fast bowler in history to claim a five-wicket haul.

Pakistan's cause appeared hopeless when Doug Bollinger rapped Imran Farhat on the pads in the seventh over, an appeal that was orginally turned down by Rudi Koertzen, the on-field umpire, but overturned by the video official. Brief periods of revival were later punctuated by Mitchell Johnson's dismissal of Salman Butt and Nathan Hauritz's removal of Faisal Iqbal, but Mohammad Yousuf and the impressive Umar Akmal survived through to stumps, still requiring a further 252 for victory on the final day.

Australia had an opportunity to seize complete control in the final half hour of play with the introduction of Simon Katich, the occasional wrist spinner, into the attack. Katich had not bowled a ball all summer to that point, but promptly had Akmal dropped by Hauritz at mid-on with his first delivery and almost stumped a ball later. Akmal survived, however, ensuring the Australians an uncomfortable night's sleep, given the difficulties they have encountered bowling teams out on the fifth day.

Two themes from this young series - Watson's nerves in the nineties and Pakistan's woes in the field - were brought to bear in the second session as Australia positioned themselves for a victory charge. Watson, whose issues converting half-centuries to three figures this summer have been well documented, was dropped by Abdur Rauf at gully off the bowling of Mohammad Aamer on 99, scampering through for a single on the misfield to seal his maiden Test ton.

For the third time this summer, Watson endured a nervous journey through the nineties. He headed to lunch unbeaten on 98, having cautiously seen off a maiden from Saeed Ajmal to close out the session. More anxious moments were to follow after the break, as Watson chased a succession of wide offerings outside off stump. Pakistan's tactic - complete with an 8-1 off-side field - appeared to have worked when the right-hander slashed a full, wide Aamer delivery to Rauf in the gully, only for the embattled fielder to turf the chance and hand Watson his century; 66 minutes after he had entered the 90s.

Pakistan's fifth dropped catch of the match ensured Watson became the first Australian batsman since Michael Hussey at The Oval to reach triple figures in a Test, breaking a team sequence of 20 unconverted half-centuries. In 12 innings as Australia's Test opener, he has now scored 716 runs at the eye-catching average of 65.09. Phillip Hughes will have a while to wait yet.

Earlier, Pakistan reprised memories of Australia's second-innings collapses during the Ashes and, more recently, the Perth Test on a spritely opening to Tuesday. Aamer emerged as the perfect weapon - relentlessly attacking a top order in pursuit of quick runs and an early declaration - to become the second youngest bowler in Test history to claim a five-wicket haul. Only Nasim-ul-Ghani, a left-arm spinner-cum-medium pacer, achieved the feat at a younger age, doing so against the West Indians more than half a century ago.

Michael Clarke was Aamer's first victim, caught behind chasing a delivery that tailed away ever so slightly. Marcus North and Brad Haddin then fell in the space of two balls as part of a double-wicket maiden in his 18th over, ensuring the 17-year-old entry into a most exclusive club.

Favouring a predominantly around-the-wicket approach to Australia's right-handers, Aamer proved destructive in the extreme with a combination of express pace, probing lengths and subtle reverse swing. His efforts put the brakes on Australia's brisk early scoring rate, but given the discrepancy between the teams' first innings totals, they always seemed likely to be in vain.